This invention relates to a manual transmission and, more particularly, to a manual transmission for a front engine front-wheel (FF) drive vehicle. Generally, the manual transmission of such type comprises: an input shaft connected to a clutch assembly; first and second intermediate shafts disposed in parallel with the input shaft; and an output shaft, which is disposed in parallel with the input shaft, to which driving force is transmitted from the input shaft via the first and/or second intermediate shaft.
In an FF drive vehicle having a transversely mounted engine, a compact transmission having a small overall length is sought to deal with vehicles that are more compact, engines that have greater numbers of cylinders and transmissions have multiple speeds. For example, as disclosed in the specification of WO 97/13990, a technique which has found wide use in recent years is to reduce the overall length of a transmission by providing a plurality of intermediate shafts.
FIG. 5 is a gear train diagram of a manual transmission disclosed in the publication of WO 97/13990.
In the prior art there is much to be desired, as discussed herein below.
As shown in FIG. 5, a first-speed gear train 1st is disposed at a position where it is farther than a reverse gear train Rev from a clutch accommodating space 62. Bearings 50b, 51b which axially support first and second intermediate shafts 50, 51, respectively, both are disposed so as to project into the clutch accommodating space 62. The fact that both of the bearings project into the clutch accommodating space 62 gives rise to the problems set forth below.
(1) The space available for clutch accommodation is reduced by the bearings for the respective intermediate shafts.
(2) A clutch assembly having the usual structure, namely one in which the release cylinder mechanism is disposed on its outer side, cannot be used because of space limitations. This makes it necessary to employ a special clutch assembly. More specifically, a so-called xe2x80x9cdirect cylinderxe2x80x9d type clutch assembly must be adopted. This is a type of clutch assembly in which the release bearing is provided with the function of the release cylinder (see the drawings in the above-mentioned specification of WO 97/13990).
(3) When a clutch assembly of direct cylinder type is used, a limitation is imposed upon hydraulic piping.
Accordingly, an object of the present invention is to provide a manual transmission that makes it possible to adopt a clutch assembly having the usual structure, particularly a compact manual transmission of small overall length for use in FF drive vehicles.
According to an aspect of the present invention, there is provided a manual transmission in which a low-speed gear train provided between an input shaft and a first intermediate shaft is disposed closer than a reverse gear train, which is provided between the first input shaft and first and second intermediate shafts, to a space accommodating a clutch assembly, whereby a new space is provided on the second intermediate shaft in an area in line with the low-speed gear train within an interior space that accommodates the transmission per se, a bearing of the second intermediate shaft being disposed in line with the low-speed gear train within the newly produced space.
According to a second aspect of the present invention, there is provided a manual transmission comprising:
an input shaft connected to a clutch assembly;
first and second intermediate shafts disposed in parallel with the input shaft;
an output shaft, which is disposed in parallel with the input shaft, to which driving force is transmitted from the input shaft via the first and/or second intermediate shaft;
a first-speed driving gear provided on the input shaft so as to co-rotate therewith;
a first-speed driven gear provided on the first intermediate shaft so as to be capable of rotating relative thereto;
a first-speed synchronizer provided on the first intermediate shaft for causing at least the first-speed driven gear to co-rotate with the first intermediate shaft in response to a shift operation;
a reverse driving gear provided on the first intermediate shaft so as to co-rotate with the first-speed driven gear;
a reverse driven gear provided on the second intermediate shaft so as to be capable of rotating relative thereto and meshed with the reverse driving gear; and
a reverse synchronizer provided on the second intermediate shaft for causing the reverse driven gear to co-rotate with the second intermediate shaft in response to a shift operation;
wherein a first-speed gear train, which is constructed by the first-speed driving gear and the first-speed driven gear provided on the input shaft and the first intermediate shaft, respectively, is disposed closer than a reverse gear train, which is constructed by the first-speed driving gear, the reverse driving gear and the reverse driven gear provided on the input shaft, the first intermediate shaft and the second intermediate shaft, respectively, to the side of the clutch assembly along the axial direction of the input shaft, with a space being produced on the second intermediate shaft in an area in line with the first-speed gear train; and
a bearing of the second intermediate shaft is disposed in the produced space in line with the first-speed gear train.
The clutch assembly may have a clutch release cylinder disposed externally thereof.
As a result of these arrangements, it is no longer necessary to dispose the bearing of the second intermediate shaft in such a manner that it projects into the clutch accommodating space, as is required in the prior art, thereby enlarging the clutch accommodating space. This makes it possible to adopt, and to connect to the manual transmission of the present invention, a clutch assembly having an ordinary structure, namely a clutch assembly having the externally disposed clutch release cylinder, which is difficult to employ in the prior art because of space limitations.
Other aspects, features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
In a preferred embodiment of the present invention, the manual transmission includes an input shaft connected to a clutch assembly, first and second intermediate shafts disposed in parallel with the input shaft, and an output shaft, which is disposed in parallel with the input shaft, to which driving force is transmitted from the input shaft via the first and/or second intermediate shaft.
In this embodiment of the manual transmission, a first-speed driven gear and a reverse driving gear are formed on the first intermediate shaft as an integral part thereof.
Preferably, a clutch assembly having an ordinary structure, especially a clutch assembly having an externally disposed clutch release cylinder, is connected to the manual transmission according to the present invention.
In a preferred embodiment of the invention, the manual transmission is constructed as a transmission having six forward speeds and one reverse speed. Depending on the particular case, the manual transmission may be constructed as a transmission having different numbers of speeds.
In a preferred embodiment of the manual transmission according to the present invention, a second-speed gear train is disposed extending between an input shaft and a first intermediate shaft. A second-speed driven gear is provided on the first intermediate shaft. The second-speed driven gear is engaged with and disengaged from the first intermediate shaft via a first-second-speed synchronizer. Third- and fourth-speed gear trains are disposed extending between the input shaft and the first intermediate shaft. Third- and fourth-speed driven gears are engaged with and disengaged from the first intermediate gear by third- and fourth-speed synchronizers mounted on the first intermediate shaft. Fifth- and sixth-speed gear trains are disposed extending between the input shaft and the second intermediate shaft. Fifth- and sixth-speed driven gears are engaged with and disengaged from the second intermediate gear by fifth- and sixth-speed synchronizers mounted on the second intermediate shaft.